GY-63_MS5611/libraries/Gauss/Gauss.h
2023-11-02 16:03:14 +01:00

170 lines
3.0 KiB
C++

#pragma once
//
// FILE: Gauss.h
// AUTHOR: Rob Tillaart
// VERSION: 0.2.1
// PURPOSE: Library for the Gauss probability math.
// DATE: 2023-07-06
#include "Arduino.h"
#define GAUSS_LIB_VERSION (F("0.2.1"))
class Gauss
{
public:
Gauss()
{
_mean = 0;
_reciprokeSD = 1; // math optimization.
}
// stddev should be positive.
bool begin(float mean = 0, float stddev = 1)
{
_mean = mean;
if (stddev == 0) _reciprokeSD = NAN;
else _reciprokeSD = 1.0 / stddev;
return (stddev > 0);
}
float getMean()
{
return _mean;
}
float getStdDev()
{
return 1.0 / _reciprokeSD;
}
float P_smaller(float value)
{
if (_reciprokeSD == NAN) return NAN;
return _P_smaller((value - _mean) * _reciprokeSD);
}
float P_larger(float value)
{
return 1.0 - P_smaller(value);
}
float P_between(float p, float q)
{
if (_reciprokeSD == NAN) return NAN;
if (p >= q) return 0;
return P_smaller(q) - P_smaller(p);
}
float P_outside(float p, float q)
{
return 1.0 - P_between(p, q);
}
float P_equal(float value)
{
if (_reciprokeSD == NAN) return NAN;
float n = (value - _mean) * _reciprokeSD;
// gain of ~10% if we allocate a global var for 'constant' c
float c = _reciprokeSD * (1.0 / sqrt(TWO_PI));
return c * exp(-0.5 * (n * n));
}
float stddevs(float value)
{
return normalize(value);
}
float normalize(float value)
{
return (value - _mean) * _reciprokeSD;
}
float denormalize(float value)
{
return value / _reciprokeSD + _mean;
}
float bellCurve(float value)
{
return P_equal(value);
}
float CDF(float value)
{
return P_smaller(value);
}
private:
float _P_smaller(float x)
{
// NORM.DIST(mean, stddev, x, true)
// these points correspond with
// 0.0 .. 3.0 in steps of 0.1 followed by 4.0, 5.0 and 6.0
float __gauss[] = {
0.50000000, 0.53982784, 0.57925971, 0.61791142,
0.65542174, 0.69146246, 0.72574688, 0.75803635,
0.78814460, 0.81593987, 0.84134475, 0.86433394,
0.88493033, 0.90319952, 0.91924334, 0.93319280,
0.94520071, 0.95543454, 0.96406968, 0.97128344,
0.97724987, 0.98213558, 0.98609655, 0.98927589,
0.99180246, 0.99379033, 0.99533881, 0.99653303,
0.99744487, 0.99813419, 0.99865010, 0.99996833,
0.99999971, 1.00000000
};
bool neg = false;
if (x < 0)
{
neg = true;
x = -x;
}
if (x >= 6.0)
{
if (neg) return 0.0;
return 1.0;
}
if (x <= 3.0)
{
int idx = x * 10;
float rv = __gauss[idx] + ((x * 10) - idx) * (__gauss[idx+1] - __gauss[idx]);
if (neg) return 1.0 - rv;
return rv;
}
// 3.0 .. 6.0
int xint = x;
int idx = 27 + xint;
float rv = __gauss[idx] + (x - xint) * (__gauss[idx+1] - __gauss[idx]);
if (neg) return 1.0 - rv;
return rv;
}
float _mean = 0;
// reciprokeSD = 1.0 / stddev is faster in most math (MUL vs DIV)
float _reciprokeSD = 1;
};
// -- END OF FILE --